1. Field of the Invention
This invention relates to an address converter for converting first addresses into second addresses which are fed to a memory in a data processing device, and more particularly to such an address converter wherein the first addresses contain first and second address words, the second addresses contain third and fourth address words and the address words represent binary numbers.
2. Description of the Prior Art
It is already well known in the art to determine the addresses of a memory in a data processing device by address substitution, which is also known as indirect addressing. In the case of address substitution of this type, the address component of the machine command is replaced by the contents of a storage cell or a register. Indirect addressing can also be carried out as addressing by base addresses and distance addresses. In this type of addressing the address component of the machine command contains the distance address which indicates the distance of a point of the store to a start of a zone, and the start of a zone is determined by the contents of a register containing the base address.
In addressing using an index register, in order to determine the actual store address, the contents of an index register is added to or subtracted from the contents of the address component of the machine command. Addressing of storage cells by means of address substitution and with the aid of the index registers has the disadvantage, however, that the conversion of the addresses requires a substantial outlay, as often it is necessary to carry out an extensive address calculation. This also results in an increase in the processing time, required for processing the individual processes, in the data processing device.